The invention described herein relates generally to a novel method and apparatus for impelling the extruded ejection of high-velocity material jets. While somewhat analogous in its function to the well-known and explosively driven shaped charge, the present invention is electrically driven.
In its basic configuration, a shaped charge is comprised of an explosive within which is disposed a cavity that is lined with metal. Detonation of the explosive collapses the metal upon its axis, thereby ejecting a metal jet. The metal jet produced by a shaped charge is of particular importance because of its ability to penetrate a variety of structural materials including armor. When used for this purpose, shaped charge metal jets typically have a velocity of about 5 to 10 millimeters per microsecond. The ability of a shaped charge metal jet to pierce protective armor coverings is most frequently increased by increasing the velocity of the jet.
In addition to shaped charges, there are many other known means for accelerating mass. For example, Janes et al in U.S. Pat. No. 3,256,687 issued June 21, 1966 disclose apparatus comprising a pair of spaced, concentric, cylindrical electrodes wherein a gaseous medium introduced between the electrodes is caused to become an electrically conductive ionized plasma and thereby establish a radial current path between the electrodes. Current flow through the plasma produces a magnetic field that accelerates the ionized plasma through an associated annulus, thereby causing a shock wave. Ionized particles and gas atoms compressed behind the shock wave cause temperature and velocity affects that result in a momentum change that imparts useful thrust to the device.
In an invention by Cheng, disclosed in U.S. Pat. No. 3,579,028 issued May 18, 1971, controlled amounts of pressurized gas are injected into a converging coaxial accelerator electrode configuration to achieve acceleration by deflagration and shaped electromagnetic field focusing. Resulting plasma is accelerated and focused to a decreasing cross section to provide dense plasma bursts for causing nuclear fusion reactions.
In Fletcher et al, U.S. Pat. No. 3,854,097 issued Dec. 10, 1974, apparatus is disclosed for compressing plasma discharged from a coaxial generator that includes a helically shaped tapered coil that is coaxially aligned with the generator. A current through the helical coil generates a time varying magnetic field that creates a radial force on the plasma. The plasma moves under high pressure and temperature to the narrow end of the coil where beads are engaged and accelerated to hypervelocities.
Schaffer in U.S. Pat. No. 4,252,605 issued Feb. 24, 1981 teaches trapping a magnetic flux in a rotating and electrically conductive liquid liner that is magnetically forced to implode by rotational energy derived from the liner. Upon expansion or rebound of the liner, rotational energy is recovered from the system.
Bohachevsky in U.S. Pat. No. 4,277,305 issued July 7, 1981 discloses discharging a capacitor bank to generate a cylindrical plasma sheath within a theta-pinch coil, and thereby heat the outer layer of a fuel element, and thus form a plasma layer thereupon. A high power photon, electron or ion beam deposites energy in either the sheath or the layer to assist in imploding the fuel element.
Kyro et al in U.S. Pat. No. 4,474,113 issued Oct. 2, 1984 provide a directed explosion effect hollow charge that comprises a mantle of the charge portion, an explosive material, a detonator, and a metal cone. The hollow charge is particularly well suited to open blocked or vaulted mine shafts.
Brattstrom et al in U.S. Pat. No. 4,481,886 issued Nov. 13, 1984 teach hollow charges and ammunition units that individually comprise a body of explosive material and an inner jet-forming cone member, together with an enclosing outer casing.
Goldstein et al in U.S. Pat. No. 4,590,842 issued May 27, 1986 disclose accelerating a projectile by supplying a pulsed high pressure and high velocity plasma jet to the rear of the projectile. The pulsed jet is derived from a dielectric capillary tube having an interior wall from which plasma forming material is ablated in response to a discharge voltage.
Herziger et al in U.S. Pat. No. 4,596,030 issued June 17, 1986 teach apparatus, for generating a plasma, that comprises concentric cylindrical electrodes that define a gas-filled discharge space. The plasma moves with high velocity towards an open end of the discharge space, and is compressed by magnetic fields at the end of an inner electrode.
Wong in U.S. Pat. No. 4,663,567 issued May 5, 1987 teaches creating first hollow and second solid coaxial cylinders of gas and then applying a high voltage, high current pulse along the common axis of the hollow and solid gaseous cylinders to cause them to implode on axis and produce a plasma.
Nevertheless, in spite of the many improvements that have been made to explosive shaped charges, and the many means that have been developed for accelerating mass, there remains a continuing need for a novel method and apparatus for impelling the extruded ejection of high-velocity material jets, particularly for purposes related to armor penetration. It would be particularly beneficial if such novel method and apparatus could provide material jets that travel at velocities in excess of the velocities of the jets provided by explosively driven shaped charges.